U.S. Pat. No. 4,105,776, issued Aug. 8, 1979, discloses, inter alia, amides of certain mercaptoacyl amino acids. Included among the amides disclosed by the patent are those having the formula ##STR1## wherein n is 0, 1 or 2; R.sub.a is hydrogen or alkyl; R.sub.b is hydrogen, alkyl, phenyl, substituted phenyl, mono-, di- or tri-phenylalkyl, alkylthiomethyl, phenylalkylthiomethyl, alkanoylamidomethyl, acyl, and others; and R.sub.c is hydrogen or hydroxy.
British patent specification No. 2,014,132, published Aug. 22, 1979 discloses, inter alia, amides, N-alkylamides, and N,N-dialkylamides (wherein the alkyl group(s) can be substituted with an amino or hydroxy substituent) of certain mercaptoacyl amino acids (the mercaptoacyl side chain contains a trifluoromethyl or pentafluoroethyl substituent).
The above described compounds inhibit the conversion of angiotensin I to angiotensin II in mammals, and are, therefore, useful in the treatment of hypertension.